Dyn Transformer voltage drop

1. Jan 29, 2015

Physicist3

1. The problem statement, all variables and given/known data

A 3MVA 11kV/415V 3 Phase Transformer has the following parameters
+ve sequence resistance = 0.00355pu
+ve sequence reactance = 0.0901pu

Primary PHASE current to the transformer is 55A and the load power factor on secondary is 0.85 lagging. Calculate voltage Drop

The attempt at a solution

R = 0.00355pu = 0.355%
X = 0.0901pu = 9.01%

Secondary current (star so line and phase current will be same) = 55 * 11000/415 = 1457.83A

R(ohms) = (10*%R*kVsecondary2)/Txfr kVA = (10*0.3555*0.4152)/3000 = 0.0002038Ω

X(ohms) = (10*%X*kVsecondary2)/kVA = (10*9.01*0.4152)/3000 = 0.0051725Ω

Φ = cos^-1(0.85) = 31.788°

Volt Drop = Sqrt(3) * 1457.83 * (0.0002038*0.85 + 0.0051725*sin(31.788)) = 7.32V

Does this mean that the voltage to the load will be 415-7.32 = 407.68V?? This is the bit I would like confirming if the remainder of the calculations happen to be correct?

Thank you :)

2. Feb 3, 2015